A couple of things to note on your post Jonathon.
Why people choose BA very often is the case of price. A similar routing ex EU for instance in BA Club from say Oslo can be had (I have done it) from around the £1800 mark. Yes, ex LHR does not offer good value generally, and like you I would choose another carrier for such a saving and a better class of service. In reality a good proportion of BA,s loading screen are fed in to LHR from around Europe.
The product (I have experience of QR) certainly is of a higher standard than BA. The ME3 are hell bent on market penetration and once they think they are there then I can see service levels deteriorating (some say QR have started already). BA is a solid product (3-4 star) that suits many people, the ME3 with their 4-5 star service suits others. Many people don’t shop around like people on this forum, but will just book on an airline they know does the trip. So BA is a natural choice for many UK citizens, and along with the feeder traffic gives BA loadings where they don’t have to compete on price from the UK.
The question I ask myself, particularly with the traditional Far East airlines struggling on the Kangaroo route is why BA does not increase capacity and offer keener pricing.